Onion Drawbacks: Odor, Eye Irritation, Digestive Effects, and Drug Interactions

Onions (Allium cepa) are nutritious but have downsides:

1. Persistent odor on breath, hands, surfaces (sulfur compounds).
2. Lachrymatory factor (syn-propanethial-S-oxide) → tearing when cut.
3. FODMAPs (fructans) → bloating, gas, pain in IBS/FODMAP-sensitive.
4. Anticoagulant interaction: Vitamin K content may affect warfarin stability.
5. Contact dermatitis in sensitive individuals.
6. GERD trigger for some.

Cooking reduces irritancy and FODMAPs. Most people tolerate moderate amounts well.